The present invention relates generally to golf clubs and manufacturing methods therefor, and more particularly, to a golf club that produces a relatively straight golf ball flight path notwithstanding a glancing impact angle, and hence produces enhanced backspin and reduced sidespin, and methods of making such a golf club.
There has been a great deal of controversy and numerous articles have been written regarding golf clubs having "square grooves". Much of the controversy deals with the amount of backspin that the club imparts to the golf ball when struck. An accomplished player has the ability to produce a great deal of backspin on the golf ball, which is readily apparent when watching a professional tournament. However, the U.S. Golf Association (USGA) has guidelines and specifications that control the depth and spacing of grooves in golf clubs that are used by players in its tournaments. Consequently, although golf club manufacturers produce clubs that have relatively square grooves, they must be manufactured to be within the USGA specifications.
Conventional clubs also cause sidespin when they strike a golf ball. When a club strikes a golf ball at a glancing angle relative to the swing path, a clockwise or counterclockwise sidespin is imparted to the ball which causes the golf ball to fade, slice, draw, or hook, depending upon the impact angle. Club manufacturers attempt to design their clubs to minimize this effect, and hence to produces a more accurate ball striking club.
Golf clubs are typically made by forging or investment casting processes. In a conventional forging process, a female mold is made having the general shape of a desired club. The female mold is placed in a mold base of a forging press. A piece of hot metal is placed in the mold, and the hot metal is pounded into a desired club shape using the press. This produces a club having rough features. Then, a grinding operation is performed on the club which produces generally smooth and finished features. Scoring lines (grooves) are then cut into the face of the club, typically by means of a set of rolling blades. After the scoring lines are formed, a second grinding operation is performed to finish forming the club. The club is then vibrated to remove residue produced by the scoring and grinding operations. The scoring lines are also sandblasted. Finally, the club is plated to produce a finished product.
In a conventional investment casting process, a master male mold is made having a desired club shape. Then a female mold is made using the master male mold. A wax member is then molded having the desired club shape using the female mold. A tree is made using a plurality of wax members, and the tree is dipped into a number of vats of ceramic "batter" having different size ceramic particles on top which successively coats the wax members with layers of ceramic. This results in a tree comprising a plurality of wax members captivated by a ceramic shell. The ceramic shell containing the plurality of wax members are then steam heated to melt the wax, thus leaving a ceramic shell having cavities therein that conform to the desired shape of the club. The shell is then heated to substantially the same temperature as molten metal that is to be poured into it. After heating the shell, molten metal is poured into the shell, and the shell is allowed to cool, leaving formed metal clubs in the cavities. The scoring lines are formed as part of the molding process. The cast clubs are then removed from the shell and each is subjected to a grinding operation to produce a desired club shape. The clubs are then vibrated to remove the residue from the grinding operation. The clubs are then polished and sandblasted to produce the finished product.
In either of these manufacturing processes, the face of the club that is produced is not flat, and in particular, the face has an uneven, wavy, cavity filled surface, due to shrinkage of the wax and metal, grinding and sandblasting. Also, the grooves (scoring lines) do not have sharp edges, in that they are generally rounded at the edges of the surface of the club face.
Accordingly, it is an objective of the present invention to provide a golf club that has a club face and groove structure that produces enhanced backspin and reduced sidespin when it strikes a golf ball, and hence produces a flight path that is relatively straight relative to the impact angle of the club on the ball. It is also an objective of the present invention to provide methods of making a golf club that produces enhanced backspin and reduced sidespin and gear effect when it strikes a golf ball.